GRAINS-Chicago grains and oilseeds fall as Black Sea, China headlines assessed

By Renee Hickman

CHICAGO, Dec 29 (Reuters) - Chicago grains and oilseeds fell on Monday in thin holiday season trade, as market players weighed how markets would be affected by news from Russia, Ukraine and China, according to analysts.

There were positive signals from talks between U.S. President Donald Trump and Ukrainian President Volodymyr Zelenskiy to end the war in Ukraine over the weekend. But those signals could be undermined by Russian claims on Monday that Ukraine had tried to attack Russian President Vladimir Putin's residence in northern Russia. Ukraine called the accusation a lie meant to undermine peace talks.

An end to the war in Ukraine would be bearish for wheat markets as removal of war risk insurance for shipping would make exports cheaper, while more Ukrainian ports could be available for wheat shipments.

On Monday, China launched its most extensive war games around Taiwan to show Beijing's ability to cut off the island from outside support in a conflict, testing Taipei's resolve to defend itself and its arsenal of U.S.-made weapons.

That flash point poses a threat to the U.S. - China trade truce, said Arlan Suderman, chief commodities economist at StoneX.

"While China has been buying a lot of soybeans, they haven't taken shipment yet, so commodity trading with China becomes a risk," he said.

Trading remained light after the Christmas holiday, and as the end of the year approached, many traders booked profits and exited the market.

"In thinly traded market conditions, this is how the market is reacting to those geopolitical stories," Suderman said.

The Chicago Board of Trade's most active wheat contract Wv1 fell 3-3/4 cents to $5.15-1/4 a bushel at 11:04 a.m. CST (1704 GMT). Soybeans Sv1 fell 8-3/4 cents to $10.63-3/4 a bushel, corn Cv1 fell 6-3/4 cents to $4.43-1/4 a bushel.